CS-03 Pressure-Volume Loop Sub-study With RV Lead Positioning

Subjects found eligible for participation in the CS-03 study, who are indicated for a de novo pulse generator implant at the center participating in this sub-study and who are not 100% dependent on RV pacing are eligible for participation in this sub-study. Patients receiving a pacemaker pulse generator exchange or who are 100% pacemaker dependent may not participate. Eligible patients will be provided with an Informed Consent specific to this sub-study and if patients choose to participate, patients will be asked to sign the Informed Consent and will then undergo the procedures described below. Patients will be prepared and draped for the Moderato implant procedure as detailed in the main CS-03 study protocol. Subjects will be instrumented prior to the Moderato Pacemaker implant procedure. The position of the RV lead will be tested at two sites known to elicit shortest QRS duration (The RV apical septum and the His region). A series of three test periods with the Moderato System programmed to deliver predetermined PHC settings will follow. Following the completion of these measurements, the conductance catheter will be withdrawn and the Moderato System implant will resume as described in the CS-03 protocol.